There are certain acts that must take place before something is a federal crime. An act that takes place entirely within State boundaries is not a federal crime, but a State crime. A physical assault with the use of hands is an example. This is why most murder cases are not federal crimes, but is instead State crimes.
The crime must involve an act that goes beyond the state lines in order to be prosecuted Federally. This includes federal lands that are within States. Tribal lands or federal military posts are examples. A crime committed on these lands is within federal jurisdiction because these are federal lands and not state lands.
An easy way to remember what other crimes might be a federal crime is to remember the Commerce Clause, Article I, Section 8 of the United States Constitution. If interstate commerce, the crossing over state lines, is used to commit the crime, then a Federal Crime has been committed. This involves many acts that you may not initially think about. Acts that involved the use of Interstate Highways, guns – which are usually made with parts from different states, ammunition – usually mad in a state different than where the gun was made, or made with parts from outside the state, mail fraud, are all examples of items used in a crime that may make for a federal offense.
The failure to involve something that crosses states lines, or on federal lands, is why many murder cases are not federal crimes. However, in the case United States v. Montgomery, discussed below, there was a kidnapping that then crossed state lines and death resulted as an act of the kidnapping across state lines. This is an example of a murder that can be prosecuted federally.
Some of you may have heard about this case, or watched reenactments on television shows. This case involves two ladies that first met at a dog show and continued discussions at an online discussion board about their breed of dog. Be forewarned, the story is a little gruesome.
UNITED STATES v. MONTGOMERY (4-5-2011)
Defendant Montgomery was convicted and sentenced to death for kidnapping, transport of kidnapping victim to another state, and death resulting from kidnapping. Defendant Montgomery killed a pregnant woman and then cut the fetus from her womb so she could claim to have given birth.
The Federal District Court held that the death resulted from the kidnapping of a person, although the mother’s death preceded the removal from the womb. The death resulted from the kidnapping, which occurred beginning with the birth and taking of the new born, and the murder was committed in furtherance of the intended kidnapping.
Here is a link to the entire opinion for some light and joyful reading: http://media.ca8.uscourts.gov/opndir/11/04/081780P.pdf